NMEA Out?

[CliveWrights]

Hi,
This is great fro reading NMEA data and I use it a lot.
Is there a way to output NMEA data via Node Red in Home Assistant.
From what I can gather the current NMEA Nodes need Signalk to be installed and running.
Cheers,
Clive.

[tomer-w]

I'm not familiar enough with Node-RED. so I asked copilot and the answer is that you can use the underlaying library easily to send the data to Node-RED. The library can output stream of json fragments for the nmea2000 messages it sense. This can be sent to Node-RED using exec node.

Sample from copilot:

CLI command (with the new --json flag)

   nmea2000-cli tcp_client --server 192.168.1.100 --port 8881 --type EBYTE --json

  This streams one JSON object per line to stdout, e.g.:

   {"PGN":127250,"id":"vesselHeading","priority":2,"source":3,"destination":255,"timestamp":"2026-03-08T14:00:00","fields":[{"id":"heading","name":"Heading","value":182.5,"unit_of_m
  easurement":"deg"}]}

  Node-RED exec node configuration

   1. Exec node — drag in an exec node, configure:
    - Command: nmea2000-cli tcp_client --server

    192.168.1.100 --port 8881 --type EBYTE --json
    - Output: select "when stdout has data" (not "when command completes") — this makes it emit a msg for each line of output
    - Timeout: leave blank (long-running)
    - Uncheck "Append msg.payload"
   2. JSON node — connect the exec node's 1st output (stdout) → a json node to parse each line into a JS object.
   3. Switch/Function node — route by PGN: // In a function node after the JSON node:
    msg.topic = "nmea2000/pgn/" + msg.payload.PGN;
    return msg;

  Flow (importable JSON)

   [
       {
           "id": "n1",
           "type": "exec",
           "command": "nmea2000-cli tcp_client --server 192.168.1.100 --port 8881 --type EBYTE --json",
           "addpay": "",
           "append": "",
           "useSpawn": "true",
           "oldrc": false,
           "timer": "",
           "name": "NMEA2000 Stream",
           "wires": [["n2"], [], []]
       },
       {
           "id": "n2",
           "type": "json",
           "name": "Parse JSON",
           "property": "payload",
           "wires": [["n3"]]
       },
       {
           "id": "n3",
           "type": "debug",
           "name": "NMEA2000 Data",
           "active": true,
           "tosidebar": true,
           "wires": []
       }
   ]

  The key setting is "useSpawn": "true" — this tells the exec node to use spawn instead of exec, streaming stdout line-by-line rather than waiting for the process to exit. Each JSON
  line arrives as a separate message in your flow.

[CliveWrights]

Hey thanks so much. I will give it a go.

[tomer-w]

Let me know how it goes.